Self-locking pin

ABSTRACT

A self-locking pin having a shaft, a headed end, and detent means biased in a bore in the pin. The portion of the detent or plunger that extends outwardly from the bore is wedge-shaped, while the portion of the plunger disposed inside the bore is cylindrical. A transitional angle is formed at the point where the configuration of the plunger changes from cylindrical to wedge-shaped. The transitional angle defines shoulders on either side of the plunger. The shaft is staked at points along the perimeter of the bore so that the inwardly extending surface created by the staking abuts the shoulders and prevents the plunger from rotating or being removed from the bore. In an alternate embodiment, the plunger may be rotated to a locked depressed position.

RELATED APPLICATION

This application is a divisional of copending U.S. patent applicationSer. No. 10/421,336, filed 23 Apr. 2003.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to fasteners, namely threadless fasteners and moreparticularly to a threadless fastener for retaining two or morestructures through apertures formed in each structure.

Detent pins are well known in industry. Many of these pins fall into thecategory of safety bolts. Safety bolts have a threaded end to which anut can be attached to as well as a detent mechanism along the length ofthe bolt. The main fastening mechanism in safety bolts is threading thenut on the end of the bolt. These products are often used in theaircraft industry so an extra safety factor is present in casevibrations cause the nut to loosen or someone forgets to tighten thenut. The detent mechanism is this extra safety factor. However, thesedual fasteners make safety bolts more difficult and thus more expensiveto manufacture. Additionally there are some applications where such abolt cannot be used because it is either impractical or impossible toaccess the threaded end of the bolt after it is inserted through anaperture. Also, screwing the nut on the end of the bolt causes anincrease in assembly time.

Cotter pins are also well known in industry. A bolt with a cotter way isinserted through an aperture. A cotter pin is then inserted through thecotter way so the bolt cannot be removed from the aperture. It is thusobvious that access to the backside of the workpiece is necessary for acotter pin to be utilized. Here again, insertion of the cotter pin inthe cotter way is an extra step that will take more time duringassembly.

There is a need in the market for a self-locking pin which is simple tomanufacture and can be installed with little effort and in applicationswhere there is no access to the opposing side of the workpiece and thusa nut cannot be applied to the threaded end of a pin.

2. Description of Prior Art

One type of prior art bolt is disclosed in U.S. Pat. No. 4,759,671 toDuran. Duran discloses a self-retaining bolt assembly in which thedetent is a solid spherically shaped ball element with cut out sectionsand these cut out sections must be configured to saddle protuberances inthe hole to prevent rotation. The periphery of the hole is peened inorder to retain the detent in the hole. The shaft and detent of thisbolt must both be machined carefully to assure a proper fit andretention for the detent.

Another prior art bolt is disclosed in U.S. Pat. No. 3,561,516 to Reddy.Reddy discloses a bolt with diametrically opposed detents slidablydisposed in one hole. Each detent has a lateral passage with a slopedcam surface. These sloped cam surfaces engage a cam member which retainsthe detents in the hole. The detents are pulled into the hole when aforce is exerted on the cam surface of the cam member by the camsurfaces of the detents. The detents are moved outwardly by the biasingmeans disposed between the detents. A number of carefully machinedparts, which are difficult to install properly, are required.Additionally, the passageway extending along the axis of the boltweakens the bolt.

A prior art bolt is disclosed in U.S. Pat. No. 2,361,491 to Nagin. Nagindisclosed a detent, generally circular in section, with a 45-degreeslope at the upper end. A V-shaped groove with plane cam faces is formedin the body of the detent. The detent is slidably disposed in a hole inthe shank. A circular passage extends along the bolt axis. A pin isslidably disposed in this passage. The pin is biased with a spring toengage the V-shaped groove and retain the detent in the hole. This boltalso must be carefully machined and installed to operate correctly.Additionally the passage in the shaft weakens the bolt.

SUMMARY OF THE INVENTION

The present invention, a self-locking pin, provides a pin with auniquely shaped detent or plunger, which facilitates easy installationof the pin through an aperture in an object. In addition, the novelplunger in combination with a staking process non-rotatably retains thedetent in its hole.

In one embodiment the self-locking pin has an elongated shaft with afirst end and a second headed end. The shaft has a hole bored in it witha plunger slidably disposed in the hole. The plunger has a lowercylindrical portion and an upper wedge-shaped portion. A shoulder isformed on the lateral sides of the plunger where these two portionsmeet. The plunger is biased in the hole. The shaft of the pin is stakedon lateral sides of the plunger with a perpendicular radius punch toretain the plunger in the hole. The location of the staking correspondsto the plunger's shoulders.

In an alternate embodiment, the plunger is formed with shoulders on itsleading and trailing sides. In this embodiment, the shaft is then stakedon the leading and trailing sides of the plunger.

In yet another embodiment, the plunger is formed with a shoulder only onits trailing side. In this embodiment, the shaft is staked on thetrailing side of the plunger.

In a final embodiment, the hole is bored through the entire shaft. Twoplungers are then disposed in the hole and each opening to the hole isstaked on lateral sides of the plungers.

The plunger can have different shapes depending upon the application.Another alternate embodiment includes a plunger that can be locked inits depressed position allowing the pin to be freely inserted or removeduntil the plunger is unlocked.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a pin in accordance with the invention.

FIG. 2 is an exploded perspective view of the pin in FIG. 1.

FIG. 2A is an alternate exploded perspective view of the pin in FIG. 1.

FIG. 2B is another alternate exploded perspective view of the pin inFIG. 1.

FIG. 2C is yet another alternate exploded perspective view of the pin inFIG. 1.

FIG. 3 is a top plan view of the pin of FIG. 1.

FIG. 4 is a side elevation view of the pin of FIG. 1.

FIG. 5 is an end elevation view of the pin of FIG. 1.

FIG. 6 is a cross sectional view of the pin of FIG. 3 taken along line6-6 of FIG. 3.

FIG. 7 is a top plan view of the wedge-shaped plunger of FIG. 2.

FIG. 8 is a front elevation view of the wedge-shaped plunger of FIG. 7.

FIG. 9 is a side elevation view of the wedge-shaped plunger of FIG. 8.

FIG. 10 is an exploded perspective view of an alternate embodiment ofthe pin of FIG. 1 with a spring retaining cavity.

FIG. 11 is a perspective view of an alternate embodiment of thewedge-shaped plunger of FIG. 2.

FIG. 11A is a perspective view of another alternate embodiment of thewedge-shaped plunger of FIG. 2.

FIG. 12 is a perspective view of a double-wedged embodiment of theplunger.

FIG. 12A is a perspective view of a conical embodiment of the plunger.

FIG. 12B is a perspective view of a radiused embodiment of the plunger.

FIG. 13 is a cross sectional view of an alternative embodiment of thepin with two wedge-shaped plungers taken along line 13-13 of FIG. 16.

FIG. 14 is a perspective view of the pin of FIG. 1 using thewedge-shaped plunger of FIG. 11.

FIG. 15 is a perspective view of the pin of FIG. 1 using thewedge-shaped plunger of FIG. 11A.

FIG. 16 is a perspective view of the pin of FIG. 13.

FIG. 17 is a side elevation view of the pin of FIG. 1 installed in anaperture through a panel.

FIG. 18 is a perspective view of another alternate embodiment pin,similar to the pin shown in FIG. 14.

FIG. 19 is a perspective view of the alternate embodiment pin showingthe plunger being locked.

FIG. 20 is a perspective view of the alternate embodiment pin with theplunger locked.

FIG. 21 is a cross-section view taken along line 21-21 of FIG. 20showing the locked plunger.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Although the disclosure hereof is detailed and exact to enable thoseskilled in the art to practice the invention, the physical embodimentsherein disclosed merely exemplify the invention, which may be embodiedin other specific structure. While the preferred embodiment has beendescribed, the details may be changed without departing from theinvention, which is defined by the claims.

FIG. 1 illustrates the presently preferred embodiment of theself-locking pin 20 according to the invention. The pin 20 has agenerally cylindrical shaft 22 with a first end 24 and a second end 26.The second end 26 may have an enlarged head 28.

As seen in FIG. 2, a re-entrant bore 30 extends partway though the shaft22 near the first end 24. The bore 30 extends radially inwardly towardsthe axis of the shaft. The bore 30 may or may not intersect the centrallongitudinal axis of the shaft. A plunger 32 is slidably disposed in thebore 30. The plunger 32 has a cylindrical portion 34 and a wedge-shapedportion 36. The plunger sits upon a helical coil spring 54. As shown inFIG. 2A, a leaf spring 70 may be used as the biasing means. As shown inFIG. 2B, compressible material 72 may be used as the biasing means. Asshown in FIG. 2C, an elastic material 74 may be utilized as the biasingmeans.

FIGS. 3, 4, and 5, show views of the pin 20 from the top, side, and endrespectively.

FIG. 6 shows a cross section of the pin 20. This illustrates the spring54 biasing the plunger 32. While the preferred embodiment uses a helicalcoil spring, other acceptable biasing means such as, but not limited to,a leaf spring, or a cushion of sufficiently elastic material could beutilized.

The plunger 32 can either sit directly on top of the spring 54, or acavity 56 can be counter-bored in the bottom surface of the plunger 32to act as a spring seat and retain the spring 54. The phantom lines inFIG. 10 denote this cavity 56.

The preferred embodiment of the plunger is further illustrated in FIGS.7, 8, and 9. The plunger 32 has a transitional angle 38 at the pointwhere the configuration of the plunger 32 changes from cylindrical 34 towedge-shaped 36. This transitional angle 38 forms a tapered shoulder 40.As will be described hereinafter, the shoulder 40 helps retain theplunger 32 in the bore 30. Referring to FIG. 9, the side of thewedge-shaped portion proximate to the first end 24 of the pin 20 is thewedge leading side 42. The side of the wedge-shaped portion proximate tothe second end 26 of the pin 20 is the wedge trailing side 44. As seenin FIG. 8, the wedge also has oppositely disposed lateral sides 46. Inthe preferred embodiment, shoulders 40 are formed on each of the lateralsides 46 of the plunger 32. An abutment 50 is formed on the sideopposite leading side 42.

As can be best seen in FIGS. 1 and 4, when the plunger 32 is in itsnormal position in the bore 30, the cylindrical portion 34 resides belowthe surface of the shaft 22 and the wedge-shaped portion 36 extendsabove the surface of the shaft 22. Referring to FIGS. 4 and 9, the wedgeleading side 42 of the plunger 32 is proximate the surface of the shaft22. The top surface of the plunger 32 extends angularly upwardly awayfrom the surface of the shaft 22 to define a ramped engaging surface 48and the abutment 50. The abutment 50 is perpendicular or normal to theaxis of the shaft 22 and faces the direction of the second end 26.

The plunger 32 and shaft 22 could be made from any suitable materialssuch as, but not limited to, alloy steels, carbon steels, stainlesssteel, or aluminum alloys.

To assemble the self-locking pin 20, the spring 54 is first placed inthe re-entrant bore 30. Next, the plunger 32 is placed in the bore 30 inthe correct orientation. The pin 20 is held in place, with the plunger32 in its depressed position, by one tool while another tool punches theshaft 22 using a radius stake punch perpendicular to the pin 20. Thestaking 52 causes a change in the shape of the shaft 22 around theentrance to the bore 30. The smooth round bore 30 is formed to asubstantially oval shape with some depth as best shown in FIGS. 2 and 3.In the preferred embodiment, the shaft 22 is staked on the lateral sidesof the wedge. The staking 52 forms inwardly extending marginal portions.This is best shown in FIG. 10. These inwardly extending portions abutthe shoulder 40 of the plunger 32 (see FIGS. 7 through 9) as the spring54 urges the plunger 32 outwardly of the bore 30. The edge of thestaking 52 abuts the flat lateral sides 46 and surface 40 of the plunger32 and prevents the plunger 32 from rotating or being removed from thebore 30. Alternately, and as shown in FIGS. 14 and 15 respectively, asingle stake may be placed behind the plunger or a pair of stakes may beplaced in front of and behind the plunger.

FIGS. 11 and 11A show first alternate embodiments of the plunger. Theplunger 132 embodied in FIG. 11 has a transitional angle 138 on only thewedge trailing side 144. This creates only one shoulder 140, which islocated on the wedge trailing side 144. Using this plunger 132embodiment, the shaft 22 is preferably staked only on the plungertrailing side as shown in FIG. 14.

The plunger 232 embodied in FIG. 11A has transitional angles 238 on boththe wedge trailing side 244 and the wedge leading side 242. This createsshoulders 240 on both the wedge trailing side 244 and the wedge leadingside 242. Using this plunger 232 embodiment, the shaft is preferablystaked on both the wedge trailing side 244 and the wedge leading side242 as shown in FIG. 15.

FIGS. 12, 12A and 12B show other alternate embodiments of the plunger.FIG. 12 depicts a double-wedge plunger 332 having opposite rampedengaging surfaces 348, 350 that meet at an edge 352. FIG. 12A shows aconical plunger 432 terminating at a point 434 and FIG. 12B depicts aradiused plunger 532 having a smooth, domed top 534. It is to beunderstood that any of the plungers could be staked in any of the pinsas described.

FIGS. 13 and 16 show an alternate embodiment of the self-locking pin 20in which two plungers 132 are utilized. As shown in FIG. 13, the twoplungers 132 are disposed in one bore 30. The plungers 132 are separatedby a spring 54, biasing each plunger 132 in an outward direction. Eachplunger 132 is of the preferred embodiment of the plunger 132. The shaft22 is staked on the lateral sides 46 of each plunger 132.

FIG. 17 shows the self-locking pin 20 inserted through an aperture. Inregular use, the self-locking pin 20 is inserted through an aperture inat least one object with a restraining surface 60. The ramped engagingsurface 48 of the plunger 32 abuts the inner surface 62 of the aperture.The force of the inner surface 62 of the aperture against the rampedengaging surface 48 of the plunger 32 causes the plunger 32 to be pushedinwardly against the bias of the spring 54 into the bore 30 until theabutment 50 is no longer exposed. The pin 20 can then be installedcompletely by continuing to push the pin 20 through the aperture. Oncethe pin 20 is installed and the ramped engaging surface 48 clears theaperture the plunger 32 pops back up against the bias of the spring 54.As shown in FIG. 17, the flat abutment 50 of the plunger 32 abuts therestraining surface 60 of the object, preventing the pin 20 from beingwithdrawn from the aperture in a similar manner.

FIGS. 18 through 21 show an alternate embodiment of the self-locking pin20 further including a lockable plunger 80. Plunger 80 includes a recess82 formed in its ramped engaging surface 48 for receiving a tool T. Asingle stake 52 is placed behind the plunger 80. When partiallydepressed (typically with the use of the tool) the plunger 80 may berotated, as shown in FIG. 19. The rotation allows plunger 80 to betrapped beneath the stake 52 and therefore hold the plunger in adepressed or retracted position (see FIG. 21). Rotating the plunger 80in either direction allows the plunger to return to its former positionwhere it can be freely depressed and extended. Alternately, theorientation of the plunger may be changed by one hundred eighty degrees(180 degrees).

The foregoing is considered as illustrative only of the principles ofthe invention. Furthermore, since numerous modifications and changeswill readily occur to those skilled in the art, it is not desired tolimit the invention to the exact construction and operation shown anddescribed. While the preferred embodiment has been described, thedetails may be changed without departing from the invention, which isdefined by the claims.

1. A self-locking pin comprising: an elongated shaft; at least onecylindrical bore intersecting said shaft; two opposed plungers, each ofsaid plungers including a cylindrical portion slidably disposed in saidbore and a wedge-shaped portion extendable outwardly of said bore, eachsaid wedge-shaped portion including a laterally extending, substantiallyplanar surface; biasing means disposed in said bore, and biasing saidplungers outwardly of said bore; said shaft being staked on at least oneside of each entrance of said bore to provide a marginal surfaceextending angularly relative to the longitudinal axis of said shaft, andfurther being engagable with each said wedge-shaped portion.
 2. Aself-locking pin as claimed in claim 1 wherein said shaft has a firstend and a second end.
 3. A self-locking pin as claimed in claim 1wherein the longitudinal axis of said bore extends substantiallyperpendicular to the longitudinal axis of said shaft.
 4. A self-lockingpin as claimed in claim 2 wherein said second end comprises an enlargedheaded portion.
 5. A self-locking pin as claimed in claim 1 wherein saidbiasing means comprises a helically wound compression spring.
 6. Aself-locking pin as claimed in claim 1 wherein said biasing meanscomprises a leaf spring.
 7. A self-locking pin as claimed in claim 1wherein said biasing means comprises a compressible material.
 8. Aself-locking pin as claimed in claim 1 wherein said biasing meanscomprises an elastic material.
 9. A self-locking pin as claimed in claim1, wherein at least a portion of the surface of each said plunger isformed to provide an angularly disposed transitional shoulder portionextending between said wedge-shaped portion and said cylindricalportion, and wherein said marginal surface is engagable with saidshoulder portion.
 10. A self-locking pin as claimed in claim 9 whereineach said wedge-shaped portion has a leading edge being positionedclosest to the first end of said shaft, said leading edge of saidwedge-shaped portion being proximate to said shaft surface and saidwedge-shaped portion extending angularly upward of said shaft to definea ramped abutting surface, said ramped abutting surface terminating inan abutment and facing the second end of said shaft.
 11. A self-lockingpin to be inserted through an aperture in at least one object whereinsaid object terminates in a restraint surface to retain the pin in theaperture, said pin comprising: an elongated shaft; a bore extendingradially inwardly through said shaft; two plungers slidably disposed insaid bore, each of said plungers having a cylindrical portion and awedge-shaped portion; biasing means disposed in said bore, and biasingsaid plungers outwardly of said bore.
 12. A self-locking pin as claimedin claim 11 wherein said shaft has a first end and a second end.
 13. Aself-locking pin as claimed in claim 12 wherein a leading edge of eachwedge-shaped portion is positioned closest to the first end of theshaft.
 14. A self-locking pin as claimed in claim 11 wherein thelongitudinal axis of said bore extends substantially perpendicular tothe longitudinal axis of said shaft.
 15. A self-locking pin as claimedin claim 12 wherein said second end comprises an enlarged headedportion.
 16. A self-locking pin as claimed in claim 11 wherein saidbiasing means comprises a helically wound compression spring.
 17. Aself-locking pin as claimed in claim 11 wherein said biasing meanscomprises a leaf spring.
 18. A self-locking pin as claimed in claim 11wherein said biasing means comprises a compressible material.
 19. Aself-locking pin as claimed in claim 11 wherein said biasing meanscomprises an elastic material.